Hi,
On Tue, 7 Aug 2007, Andrew Morton wrote:
> > The current msleep is fine and doesn't need any "fixing".
> > Not all the world is i386, _please_ keep hrtimer usage where it's
> > required. Simple timer should be given preference unless the higher
> > resolution is really needed, which is not the case here.
>
> Hang on. Having msleep(1) sleep for 20 milliseconds is really awful
> behaviour. Possibly worse is the fact that with other configs, it will
> delay for eight milliseconds. Or two. That's an order of magnitude of
> unpredictability which can actually cause driver breakage.
>
> Fixing that *bug* is a good thing. I see no reason why we should "keep
> hrtimer usage where it is required"? The implementation details are hidden
> from the caller.
This is not a bug. You have to keep in mind that for hrtimer to make a
real difference HIGH_RES_TIMERS has to be enabled, OTOH if HZ is already
set to 1000, it doesn't make much difference.
The sleep was and will be only a minimum time, expecting something
different is actually a bug.
> > so below is a nanosleep implementation based
> > on Jonathan's patch. This will user give a choice, so there is no need to
> > force all users to use hrtimer for a simple sleep.
>
> But apart from needlessly fattening the kernel API, that leaves us in the
> current situation where an unknown number of the msleep() callers actually
> care that they are calling a function which by a huge margin fails to do
> what they are asking it to do. It will take a long time to hunt down all
> the problematic callsites and migrate them to nanosleep().
As I tried to say before this is foremost an API issue. Introducing
nanosleep() makes it clear that this user will benefit from enabling
HIGH_RES_TIMERS, whereas msleep() says that resolution is not that
important and thus it will work fine without HIGH_RES_TIMERS and/or
HZ_1000.
bye, Roman
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
